The purpose of this research is to measure the influence of abnormal red cell shape, size, and deformability on oxygen exchange by flowing blood. The project is divided into three phases. In the first, through evaluation of several processes and agents which physically alter erythrocytes, we hope to improve understanding of causes of changes in erythrocyte shape, size, and deformability. In the second phase, the effects of these physical changes on the oxygen transport function of red cells will be examined at various shear rates in an in vitro model, and, in the third phase, the effects of these same erythrocyte abnormalities on tissue metabolism and function will be examined in isolated rabbit heart preparation. BIBLIOGRAPHIC REFERENCES: Rand, P. W.: Hemoglobin-oxygen affinity and tissue oxygen delivery. J. Maine Med. Assoc., 67:9-12, 1976. Norton, J. M., Rand, P. W., and Macalaster, E. G.: Influence of red cell oxygen affinity and physical properties on oxygen exchange. J. Maine Med. Assoc., 67:13-14, 1976.